In recent years, industrial developments have caused various environmental problems due to pollutants caused by rapid economic growth, population growth and urbanization.
That is, pollutants such as wastewater, heavy metals, dust and harmful gas are discharged from manufacturing plants and industrial facilities of various industries, living facilities, automobiles and motorcycles, thereby polluting air and water quality.
These pollutants are interfering with the life of human being who wants to live pleasant and healthy life, and various solutions to purify the pollutants have been sought, and the research and development for this have been continuously and variously continued.
An example technique for purifying contaminants is to filter the contaminated gas through a membrane.
Membranes can separate and filter only certain components from gases, liquids, solids or mixtures thereof, and the mixture is filtered using the physicochemical properties of the membrane.
Filters that filter contaminants by using such membranes are widely used in various industrial fields. Particularly, there are various types of gas filters for purifying contaminated air. In order to have more advanced functions, research on gas filters has been conducted continuously.
Meanwhile, a polymer membrane which can be applied to a membrane of a gas filter is prepared by casting a polymer solution to form a sheet, and then immersing the formed sheet in a solid phase. Polymer membranes are used as a wide range of membranes.
Korean Patent Application Publication No. 2011-85096 proposed a composite filter in which activated carbon fibers and ion exchange fibers are laminated on a side wall of a housing. However, there was a disadvantage that the size of the filter is large in the form of a composite filter.
Korean Patent Registration Publication No. 507969 proposed a technique of producing a web by forming a web of ion exchange fiber on an ion exchange nonwoven fabric, sprinkling ion exchange resin on the web, placing an ion exchange nonwoven fabric thereon, and removing ionic gas such as acidic or alkaline present in a clean room of a semiconductor manufacturing process, with a non-woven type composite ion exchange filter using needle punching. However, since the pores of the nonwoven fabric are large, the very fine harmful dust cannot be filtered, and the ion exchange resin sprayed on the ion exchange nonwoven fabric may flow to thereby cause an additional source of pollution to occur.
Korean Patent Registration Publication No. 1491994 discloses a membrane for a gas filter including a porous support that is prepared by electrospinning a spinning solution through a nozzle having a ratio of the distance from the tip of the nozzle and the distance from the center of the nozzle is 1.01 to 1.1 in which polyimide nanofibers are bonded in the form of a non-woven fabric having a plurality of pores. However, when the membrane for a gas filter is implemented solely into a gas filter, and the gas passes through the gas filter at high speed, damage or deformation of the membrane occurs to cause lowering of reliability.